Method of producing comparatively rigid containers by the repeated immersion of a core in film-producing substances



Dec. 8, 1942. BRATRlNG 2,304,676 METHOD OF PRODUCING COMPARATIVELY RIGID CONTAINERS BY THE REPEATED IMMERSION OF A CORE IN FILM-PRODUCING SUBSTANCES Filed Nov. 18, 1937 v Fig. 2

ES PATENT METHOD OF rnonoomc mmmmm mom CONTAINERS BY THE nnrmran nummsron or A cone in mm-raonuc- I ING SUBSTANCES Kurt Bratring, Dahlem, Berlin, Germany, as-

signor, by mesne'assignments, to Neocell Prod Application ucts Corporation, a corporation of Delaware November 18, .1937, Serial Germany December 3, 193

,3lClaims, (Cl. 2 29-45) This invention relates to a method of producing comparatively rigid containers for packing purposes.

, Rigid containers composed of sheet metal or cardboard have already been proposed having a lining or bag of paper or cellulose hydrate material loosely fittedtherein. These packings are employed more particularly for pulverulent substances, but have the disadvantage that the pulverulent substance tends to penetratebetween the rigid outer container and the inner bag or lining, so that the intended protection of the contents of the container is to a certain extent again annulled.

Seamless containers consisting of a-transparent cellulose material and having a thin and rigid wall have also been proposed for packing medicaments, foodstuffs and other commodities of the most difierent kinds. These containers are formed by the repeated immersion of cores or moulds in a film-producingsubstance, such as a solution of acetyl cellulose in acetone, layer by layer until the desired thickness has been attained, whereupon the containers'are dried and then removed from thecores. To furnish these containers with a lid or top it is necessary to produce the container proper and thelidor top on two separate cores having slightly diiierent diameters, which are so adapted to each other that the finished lid will fit over the ilnished'container.

It is the object ofthe invention to produce in one operation-by the immerision process a con-' tainer which is capable of being closed or'sealed and possesses a comparatively rigid main portion suflicient toaccommodate the contents of the container and a thin-walled upper portion a which can be formed into a seal by folding, bend ing over or twisting together in the manner of a bag. The upper portion must naturally-be so thin thatit is capable of being folded or otherwise 'varied in its form.

In accomplishment of this object the inventionaccordingly comprises a method of producing comparatively rigid containers, which consists in immersing a core in a film-producing sub-- stance, such as acetyl cellulose, and repeating such immersion-until a film has been produced on the said core of a certainlimited thickness which still permits of a variation in the form of the said film, and thereupon continuing the immersion of the said core, but to a' depth which is less than before, such continued immersion being repeated until a comparatively rigid wall has been .formed corresponding in extent to the reduced depth of immersion, In this manner there is obtained by immersion in one single operation a seamless container which possesses a comparatively .thick wall up to a height which may be made dependent on the quantity of material to be introduced therein, and from that point a comparatively thin film-like wall of such thickness that it is capable of being folded or otherwise varied in its form so as to seal oif the container against the outside.

The number of immersions necessary for producing the comparatively rigid lower portion and the thin upper portion will depend on the nature of the film-producing substance.

The method according to the invention may be utilised for the production of round, elliptical,

, square or polygonal containers of desired size.

It may also be modified in such fashion that there is first produced by immersion the lower rigid wall portion, whereupon the thin-walled upper portion is formed by continued immersion to a greater depth. 'If desired, the thin upper portion may have a greater diameter than the rigid lower portion.

In certain instances it may be desirable to em ploy for the thin upper portion a solution of a different composition to that employed for the rigid lower portion. Containers of this kind consisting 1 of. two difierent materials canalso be produced quite. readily in one operation, and it is merely necessary to provide two separate immersiontanks. For example, there'may be employed for the formation of the thin upper portion a solution of acetyl cellulose in acetone containing a comparatively large proportion of softening agent in order to make the thin-walled upper portion particularly capable of being varied in form, and

, water-repelling additions may also be incorporated in this portion, whilst for the rigid lower portion there maybe .employed another cellulose product, such as benzyl cellulose. In certain instances the diflerence between the two solutions employed may consist merely in the addition of diiferentdyestufls, so that the thin upper portion capable of being varied in its form is rendered distinguishable by its difierent'colour. If desired, these colour additions may also be opacity producing pigments, such as titaniumoxide.

When using difierent substances for producing the container it is also quite possible to weld the two parts of the container togetherii in the substance for producing the rigid wall portion solvents are employed which arecapable of dissolving the substance from which the other por-' tion ot'the container is produced. Thus, for example, it is quite readily possible to employ with;

' yond the upper edge of the -actual wall in advantage for the production of an inner layer. which is highly impervious a solution of caoutchouc, caoutchouc chloride or a polyvinyl compound in a suitable solvent if for the rigid outer layer there is used, for example, a solution of acetyl cellulose in methylene chloride with the addition oi methanol, phthalic ethyl ester or other suitable substances. .A container which is particularly suitable for packing purposes is obtained if a layer of a polyvinyl chloride in methylene chloride is first allowed to form on a core for the purpose of producing a thin waterproof inner film, and then a second solution is employed, which consists of acetyl cellulose dissolved in acetone. After re; moval from the core a transparent container is obtained having an upper portion which is readily capable of being folded or otherwise varied in its form for the purpose of sealing the contents of the container againstthe outside, but the inner portion of which container can be readily detached as'necessity arises step by step from the rigid outer portion merely by a pulling action thereon. The advantage of this form of, container consists in the fact that as the contents or the container are removed the innerfllmcan always be pressed down tightly against the remaining contents, for example in the case of a pulverulent material, tea or the like.

Possible embodiments of containers produced according to the invention are illustrated-in the accompanying drawing. 1 Figs. 1 and 2 are perspective views of one embodiment of container according to the invention in the open and closed condition respectively.

Figs. 3 and 4 are similar views of a cylindrical container. a

Fig. 5 illustrates in perspective view a modified form of cylindrical container. In Figs. 1 and 2 the container possesses a hexagonal cross-section. The container proper a, the height of which depends on the quantity of material to be introduced therein, continues bethe formof a comparatively thin portion b, which is capable of being in form, and when folded can be made to rest against the contents of the container a in the 'manner shown in Fig. 2.

In Figs. 3 and 4 the container c is cylindrical. Fig. 4 shows the manner per portion d can'be twisted together over the comparatively rigid wall portion and secured by means of a clip c.

Fig; shows a'container which-is set together and composed of difierent substances, and the inner film-like portion 9 of which may be detached from the rigid outer portion fby a pulling action thereon, so that the thin and impervious inner portion g may always be reduced in size more and more to agree with the remaining contents of the container. A container of this kind can also be furnished with a conventional lid h.

In carrying-out the method according to the invention the procedure, for example in the production of a container according to Fig. l, is such that on a core or hexagonal cross-section and having,'ior example, amaximum diameter or 60 mm. there is produced by single or twofold immersion to a'height of, say, 90 mm. a wall having a thickness oi,'say,- .05 mm. When this layer is dry the immersion is continued, but the depth of immersion is decreased to, say, 60 This continued immersion is repeated so many times I until the lower portion of the container, in a height or 60 mm., is coated with a layer of .3 mm. in thickness. vW'hen the container has suf flciently dried on the core it can be detached.

Itwill be understood that no limitation is made to the particular embodiments illustrated in the drawing, and that numerous modifications are quite possible within the meaning of the above'description and the'annexed' claims without departing from the spirit of the invention.

What I claim as new and desire to Letters Patent is: e a l.' A container comprising a relatively thick rigid portion or cellulosic material shaped to form the bottom and upstanding side walls of said container, and a relatively thin pliable layer of the same material positioned adjacent the entire inner surface of said rigid to form ,a homogeneous layer and extending above the upper edge of said rigid layer as a flexible closure element of substantially uniform thickness, the bond between said rigid layer and said flexible layer being effected without added adhesive. 3

2. A container comprising an upper portion adapted to be formed into-a closure, said upper.

thin pliable portion consisting oi a relatively layer of a synthetic plastic material of substantially uniform thickness, and a lower portion adapted to form the body of said container, said lower portion comprising an integral extension of said thin flexible upper portion f and an outer folded or otherwise variedof said outer layer, the

in which the thin upsubstantially rigid layer to which said extension is-bonded, said outer layer comprising synthetic plastic material and forming the bottom and side walls of said container, said innerlayer being bonded to substantially the entire inner surface bondbetween said layers being an autogenous bond.

3. A container comprising an upper portion adapted to be formed into a closure, said upper .portion consisting of a relatively thin pliable I layer of a synthetic plastic material of substane tially uniform thickness, and a. lower portion adapted to form the body of lower portion comprising an said container, said integral extension of said thin flexible upper portion" and an'outer substantially rigid layer 'is"bonded,said outer layer comprising synthetic plastic material and forming the bottom and side walls or said container, said inner layer being bonded to substantially the entireinner surface or said outer layer, the bond between said layers being an autogenous bond, both of said layers being of the same plastic material.

,.- KURT BRA'I'RING.

secure by layer and bonded thereto.

to which said extension. 

